Lagging Performance On Brand New Laptop?

I just bought a brand new Dell XPS 15 laptop. It has the new i-7 2630 processor, 8 gigs of RAM, 1gb nvidia 525m video card, 750 gigs WD hard drive, R+GBLED display (1920 x 1080), etc. As soon as I received it, I performed a clean install of Windows 7 HP. All the updates and drivers are current.It feels as though something is always running in the background and it's seriously screwing up my experience. The whole thing just lags. For example, whenever I edit posts in Wordpress, it takes forever to delete characters while typing (I'm using FF6). Going back and forth between Thunderbird and say MS Word takes like two seconds to switch between the windows.The interesting part is I'm not playing any games or running programs that are draining the memory. In fact, I only have MS Office, FF, Thunderbird, Adobe Reader, and Skype installed. And yet the performance sucks. The whole system feels like it's lagging, nothing is smooth. Moreover, the fan is on almost all the time, which was almost non-existent with the older system.

The system is replacing my Dell Inspiron 1545 which despite having only the Core 2 Duo processor, half the memory of this one, and on-board graphics, it works far smoother than this one with no lag whatsoever.I tried isolating the problem by minimizing the number of start-up applications but it did no good. Next I used the built in "display quality troubleshooter" and the report came back as "visual effects settings aren't optimized for best performance". But then again, the settings are exactly the same as the Inspiron. And that system ran fine on on-board graphics, let alone a dedicated graphics card available on this system.